This invention is generally directed to hydroxygallium phthalocyanines and photoconductive imaging members thereof, and, more specifically, the present invention is directed to tetrafluoro substituted phthalocyanines, photoconductive imaging members thereof, and processes for the preparation thereof. In embodiments, the processes of the present invention comprise the reaction of fluorophthalonitrile with a gallium halide, preferably a gallium chloride in an organic solvent like N-methylpyrrolidone, a halonaphthalene such as 1-chloronaphthalene, quinoline, and preferably 1-chloronaphthalene, and the like to provide the precursor pigment tetrafluoro halogallium phthalocyanine, and preferably tetrafluoro chlorogallium phthalocyanine, subsequently hydrolyzing or acid pasting the aforementioned precursor to preferably provide tetrafluoro hydroxygallium phthalocyanine Type I; and thereafter mixing the Type I in the presence of certain solvents, such as N,N-dimethylformamide, dimethylaminoethanol, isopropanol, and preferably N-methylpyrrolidone to enable a unique polymorphic form of tetrafluoro hydroxygallium phthalocyanine for each solvent that is used, including a very light sensitive Type V tetrafluoro hydroxygallium phthalocyanine. Embodiments of the present invention relate to certain tetrafluoro hydroxygailium phthalocyanines, such as Type I, II, III, IV, and V, processes thereof, and photoconductive imaging members thereof. Moreover, in embodiments the present invention relates to mixtures of tetrafluoro hydroxygallium phthalocyanines and hydroxygallium phthalocyanines, processes thereof, and photoconductive imaging members thereof.
With the present invention, in embodiments there is provided Type V tetrafluoro hydroxygallium phthalocyanine with an X-ray powder diffraction trace having a major peak at Bragg angles of 6.6, and minor peaks at 6.0, 13.4, 14.7, 15.9, 16.9, 26.1, and 27 degrees 2.THETA.; Type I tetrafluoro hydroxygallium phthalocyanine with an X-ray powder diffraction trace having a major peak at Bragg angles of 6.5, and minor peaks at 15.6, and 26.5 degrees 2.THETA.; Type II tetrafluoro hydroxygallium phthalocyanine with an X-ray powder diffraction trace having a major peak at Bragg angles of 6.6, and minor peaks at 12.7, 15.4, 26.3, and 27.0 degrees 2.THETA.; Type III tetrafluoro hydroxygallium phthalocyanine with an X-ray powder diffraction trace having a major peak at Bragg angles of 7.5, and minor peaks at 9.1, 15.6, 16.5, 19.5, 21.8, 22.6, and 27.3 degrees 2.THETA.; and Type IV tetrafluoro hydroxygallium phthalocyanine with an X-ray powder diffraction trace having a major peak at Bragg angles of 6.5, and minor peaks at 7.5, 15.2, 15.7, and 26.5 degrees 2.THETA..
More specifically, in embodiments the process of the present invention comprises the formation of a precursor prepared by the reaction of 1 weight part, or weight percent gallium chloride with from about 1 weight part to about 10 weight parts and preferably about 4 weight parts 4-fluorophthalonitrile in a solvent, such as quinoline, chloronaphthalene, or N-methylpyrrolidone, and which solvent is selected in an effective amount such as, for example, from about 5 weight parts to about 100 weight parts and preferably about 15 weight parts, for each part of gallium chloride that is used, to provide a pigment precursor tetrafluoro chlorogallium phthalocyanine, which is subsequently washed with a component, such as dimethylformamide, to provide the precursor tetrafluoro chlorogallium phthalocyanine as determined by X-ray powder diffraction, with an X-ray powder diffraction trace having peaks at Bragg angles of 16.5, 25.5, 26.2, 27.3, and 28.8 and the highest peak at 7.0 degrees 2.THETA.); dissolving 1 weight part of the resulting precursor pigment tetrafluoro chlorogallium phthalocyanine in concentrated, about 94 percent, sulfuric acid, which acid is selected in various effective amounts, such as in an amount of from about 1 weight part to about 100 weight parts and in an embodiment about 25 weight parts, by stirring the pigment precursor tetrafluoro chlorogallium phthalocyanine in the acid for an effective period of time, for example from about 30 seconds to about 24 hours, and in an embodiment about 2 hours at a temperature of from about 0.degree. C. to about 25.degree. C., and preferably below about 10.degree. C. in air or under an inert atmosphere, such as argon or nitrogen; adding the resulting mixture in a dropwise manner at a rate of about 0.5 milliliter per minute to about 10 milliliters per minute, and in an embodiment about 1 milliliter per minute to a stirred organic solvent, which can be a mixture comprised of from about 1 volume part to about 10 volume parts and preferably about 4 volume parts of concentrated aqueous ammonia solution (14.8N) and from about 1 volume part to about 10 volume parts, and preferably about 6 volume parts of water for each volume part of acid like sulfuric acid that was used, which solvent mixture was chilled to a temperature of from about -25.degree. C. to about 10.degree. C. and in an embodiment about -5.degree. C. while being stirred at a rate sufficient to create a vortex extending to the bottom of the flask containing the solvent mixture; isolating the resulting blue pigment by, for example, filtration; and washing the tetrafluoro hydroxygallium phthalocyanine product obtained with deionized water by redispersing and filtering from portions of deionized water, which portions are from about 10 volume parts to about 400 volume parts and in an embodiment about 200 volume parts for each weight part of precursor pigment tetrafluoro chlorogallium phthalocyanine which was used. The product obtained as a wet cake, approximately 10 percent by weight pigment and 90 percent by weight water, can then be oven dried at a temperature of from about 40.degree. C. to about 65.degree. C. and in an embodiment about 50.degree. C. for a period of from about 12 hours to about 1 week and in an embodiment about 24 hours. The product, a dark blue solid, Type I tetrafluoro hydroxygallium phthalocyanine, had an X-ray diffraction pattern having major peaks at 6.9, 13.1, 16.4, 21.0, 26.4, and the highest peak at 6.9 degrees 2.THETA.. The resulting dried intermediate product, Type I tetrafluoro hydroxygallium phthalocyanine, can then be converted to different polymorphic forms by stirring in the presence of a solvent, present in an amount of from about 1 weight part to about 50 weight parts and in an embodiment about 15 weight parts per weight part of Type I tetrafluoro hydroxygallium phthalocyanine that was used, at room temperature, about 25.degree. C., for a period of from about 2 hours to about 2 weeks, and in an embodiment about 1 week. The stirring can be effected with a magnetic stirrer, or in an embodiment, by placing said pigment and said solvent in a sealed glass jar containing glass beads, 1 mm in diameter, present in an amount of from about 10 weight parts to about 100 weight parts and in an embodiment about 30 weight parts per weight part of Type I tetrafluoro hydroxygallium phthalocyanine that was used, and milling said pigment/solvent mixture on a ball mill. In one invention embodiment there is used, for example, N,N-dimethylformamide as the solvent, which results in the product, Type II tetrafluoro hydroxygallium phthalocyanine. In another separate embodiment of the present invention there is used, for example, dimethylaminoethanol as the solvent, which results in the product, Type III tetrafluoro hydroxygallium phthalocyanine. In another separate embodiment there is used, for example, isopropanol as the solvent, which results in the product, Type IV tetrafluoro hydroxygallium phthalocyanine. In another separate embodiment there is used, for example, N-methylpyrrolidone as the solvent, which results in the product, Type V tetrafluoro hydroxygallium phthalocyanine.
Examples of advantages associated with the present invention in embodiments thereof include excellent dispersion quality, as observed by careful visual inspection of the coating of the photogenerating layer containing the pigment Type V tetrafluoro hydroxygallium phthalocyanine; broad spectral response of the Type V pigment extending into the infrared region of the spectrum, and in embodiments from about 500 to about 900 nanometers, excellent xerographic characteristics, such as high photosensitivity, for example from about 75 to about 125, and in an embodiment about 100 Vcm.sup.2 /erg, low dark decay, for example from about 0 to about 20, and in an embodiment about 11 volts/second, and low residual voltage of, for example, from about 0 to about 20, and in an embodiment about 11 volts; compatibility with HOGaPc; and the potential for one pot preparation.
The tetrafluoro hydroxygallium phthalocyanines, especially the Type V obtained, can be selected as organic photogenerator pigments in layered photoresponsive imaging members with charge transport layers, especially hole transport layers containing hole transport molecules such as known tertiary aryl amines. The aforementioned photoresponsive, or photoconductive imaging members can be negatively charged when the photogenerating layer is situated between the hole transport layer and the substrate, or positively charged when the hole transport layer is situated between the photogenerating layer and the supporting substrate. The layered photoconductive imaging members can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic imaging and printing processes wherein negatively charged or positively charged images are rendered visible using toner compositions of appropriate charge polarity. In general, the imaging members are sensitive in the wavelength region of from about 550 to about 900 nanometers, and in particular, from 700 to about 850 nanometers, thus diode lasers can be selected as the light source.
In Bull. Soc. Chim. Fr., 23 (1962), there is illustrated the preparation of hydroxygallium phthalocyanine via the precursor chlorogallium phthalocyanine. The precursor chlorogallium phthalocyanine is prepared by reaction of o-cyanobenzamide with gallium chloride in the absence of solvent. O-cyanobenzamide is heated to its melting point (172.degree. C.), and to it is added gallium chloride at which time the temperature is increased to 210.degree. C. for 15 minutes, and then cooled. The solid is recrystallized out of boiling chloronaphthalene to give purple crystals having carbon, hydrogen and chlorine analyses matching theoretical values for chlorogallium phthalocyanine. Dissolution in concentrated sulfuric acid, followed by reprecipitation in diluted aqueous ammonia, affords material having carbon, and hydrogen analyses matching theoretical values for hydroxygallium phthalocyanine.
There are illustrated in JPLO.221459 certain gallium phthalocyanines and which phthalocyanines have the following intense diffraction peaks at Bragg angles (2 theta.+-.0.2.degree.) in the X-ray diffraction spectrum,
1- 6.7, 15.2, 20.5, 27.0
2- 6.7, 13.7, 16.3, 20.9, 26.3 (hydroxygailium phthalocyanine Type I)
3- 7.5, 9.5, 11.0, 13.5, 19.1, 20.3, 21.8, 25.8, 27.1, 33.0 (chlorogallium phthalocyanine Type I).
In the Proceedings of the 9th International Congress on Advances in Non-Impact Printing Technologies, Watanabe et al. describe unsuccessful attempts to prepare highly photosensitive polymorphic forms of substituted titanyl phthalocyanines. F.sub.4 -TiOPc, Cl.sub.4 -TiOPc, and (NO.sub.2).sub.4 TiOPc were all subjected to acid pasting and polymorphic conversion methods. Despite varying conditions for the conversion process, the highly sensitive Type IV polymorph was not observed, and apparently only when unsubstituted TiOPc was selected did the Type IV polymorph result.
Layered photoresponsive imaging members have been described in a number of U.S. Patents, such as U.S. Pat. No. 4,265,900, the disclosure of which is totally incorporated herein by reference, wherein there is illustrated an imaging member comprised of a photogenerating layer, and an aryl amine hole transport layer. Examples of photogenerating layer components include trigonal selenium, metal phthalocyanines, vanadyl phthalocyanines, and metal free phthalocyanines. Additionally, there is described in U.S. Pat. No. 3,121,006 a composite xerographic photoconductive member comprised of finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. The binder materials disclosed in the '006 patent comprise a material which is incapable of transporting for any significant distance injected charge carriers generated by the photoconductive particles.
The use of certain perylene pigments as photoconductive substances is known. There is thus described in Hoechst European Patent Publication 0040402, DE3019326, filed May 21, 1980, the use of N,N'-disubstituted perylene-3,4,9,10-tetracarboxyldiimide pigments as photoconductive substances. Specifically, there is, for example, disclosed in this publication N,N'-bis(3-methoxypropyl)perylene-3,4,9,10-tetracarboxyldiimide dual layered negatively charged photoreceptors with improved spectral response in the wavelength region of 400 to 700 nanometers. A similar disclosure is revealed in Ernst Gunther Schlosser, Journal of Applied Photographic Engineering, Vol. 4, No. 3, page 118 (1978). There are also disclosed in U.S. Pat. No. 3,871,882 photoconductive substances comprised of specific perylene-3,4,9,10-tetracarboxylic acid derivative dyestuffs. In accordance with the teachings of this patent, the photoconductive layer is preferably formed by vapor depositing the dyestuff in a vacuum. Also, there are specifically disclosed in this patent dual layer photoreceptors with perylene-3,4,9,10-tetracarboxylic acid diimide derivatives, which have spectral response in the wavelength region of from 400 to 600 nanometers. Also, in U.S. Pat. No. 4,555,463, the disclosure of which is totally incorporated herein by reference, there is illustrated a layered imaging member with a chloroindium phthalocyanine photogenerating layer. In U.S. Pat. No. 4,587,189, the disclosure of which is totally incorporated herein by reference, there is illustrated a layered imaging member with a perylene pigment photogenerating component. Both of the aforementioned patents disclose an aryl amine component as a hole transport layer.
In U.S. Ser. No. 07/537,714, filed Jun. 14, 1990, now abandoned, the disclosure of which is totally incorporated herein by reference, there are illustrated photoresponsive imaging members with photogenerating titanyl phthalocyanine layers prepared by vacuum deposition. It is indicated in this copending application that the imaging members comprised of the vacuum deposited titanyl phthalocyanines and aryl amine hole transporting compounds exhibit superior xerographic performance with low dark decay characteristics and high photosensitivity, particularly in comparison to several prior art imaging members prepared by solution coating or spray coating, reference for example U.S. Pat. No. 4,429,029 mentioned hereinbefore.
In U.S. Pat. No. 5,153,313, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of phthalocyanine composites which comprises adding a metal-free phthalocyanine, a metal phthalocyanine, a metalloxy phthalocyanine or mixtures thereof to a solution of trifluoroacetic acid and a monohaloalkane; adding to the resulting mixture a titanyl phthalocyanine; adding the resulting solution to a mixture that will enable precipitation of said composite; and recovering the phthalocyanine composite precipitated product.
In U.S. Pat. No. 5,166,339, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of titanyl phthalocyanine which comprises the reaction of titanium tetrapropoxide with diiminoisoindolene in N-methylpyrrolidone solvent to provide Type I, or .beta.-type titanyl phthalocyanine as determined by X-ray powder diffraction analysis; dissolving the resulting titanyl phthalocyanine in a mixture of trifluoroacetic acid and methylene chloride; adding the resulting mixture to a stirred organic solvent, such as methanol, or to water; separating the resulting precipitate by, for example, vacuum filtration through a glass fiber paper in a Buchner funnel; and washing the titanyl phthalocyanine product.
Disclosed in U.S. Pat. No. 5,164,493 is a process for the preparation of titanyl phthalocyanine Type I which comprises the addition of titanium tetraalkoxide in a solvent to a mixture of phthalonitrile and a diiminoisoindolene, followed by heating. The disclosure of this application is totally incorporated herein by reference. Disclosed in U.S. Pat. No. 5,189,156 is a process for the preparation of titanyl phthalocyanine Type I which comprises the reaction of titanium tetraalkoxide and diiminoisoindolene in the presence of a halonaphthalene solvent; and in U.S. Pat. No. 5,206,359 is a process for the preparation of titanyl phthalocyanine which comprises the treatment of titanyl phthalocyanine Type X with a halobenzene, the disclosures of which are totally incorporated herein by reference.
Illustrated in U.S. Pat. No. 5,382,493, the disclosure of which is totally incorporated herein by reference, are processes for the preparation of Type II dihydroxygermanium phthalocyanine, which comprises the reaction of phthalonitrile or diiminoisoindolene with tetrahalogermanium or tetraalkoxygermanium in a suitable solvent.
Also, in U.S. Pat. No. 5,473,064, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of hydroxygallium phthalocyanine Type V, essentially free of chlorine, whereby a pigment precursor Type I chlorogallium phthalocyanine is prepared by reaction of gallium chloride in a solvent, such as N-methylpyrrolidone, present in an amount of from about 10 parts to about 100 parts, and preferably about 19 parts with 1,3-diiminoisoindolene (Dl.sup.3), in an amount of from about 1 part to about 10 parts, and preferably about 4 parts Dl.sup.3 for each part of gallium chloride that is reacted; hydrolyzing the resulting pigment precursor chlorogallium phthalocyanine Type I by standard methods, for example acid pasting, whereby the pigment precursor is dissolved in concentrated sulfuric acid and then reprecipitated in a solvent, such as water, or a dilute ammonia solution, for example, from about 10 to about 15 percent; and subsequently treating the resulting hydrolyzed pigment hydroxygallium phthalocyanine Type I with a solvent, such as N,N-dimethylformamide, present in an amount of from about 1 volume part to about 50 volume parts and preferably about 15 volume parts for each weight part of pigment hydroxygallium phthalocyanine that is used by, for example, ball milling said Type I hydroxygallium phthalocyanine pigment in the presence of spherical glass beads, approximately 1 millimeter to 5 millimeters in diameter, at room temperature, about 25.degree. C., for a period of from about 12 hours to about 1 week, and preferably about 24 hours such that there is obtained a hydroxygallium phthalocyanine Type V, ball milling contains very low levels of residual chlorine of from about 0.001 percent to about 0.1 percent, and in an embodiment about 0.03 percent of the weight of the Type V hydroxygallium pigment, as determined by elemental analysis.
Also, processes for the preparation of hydroxygallium phthalocyanines are illustrated in copending patent applications U.S. Ser. No. 413,554, filed Mar. 30, 1995, U.S. Pat. No. 5,482,811, U.S. Pat. No. 5,466,796, U.S. Ser. No. 233,834, now U.S. Pat. No. 5,521,306, U.S. Pat. No. 5,493,016 and U.S. Pat. No. 5,456,998, the disclosures of each being totally incorporated herein by reference.
In copending application U.S. Ser. No. 510,730, filed concurrently herewith, and the disclosure of which is totally incorporated herein by reference, there is illustrated a photoconductive imaging member comprised of a supporting substrate, a blocking layer, a photogenerating layer, and a charge transport layer, and wherein said photogenerating layer is comprised of a mixture of a hydroxygallium phthalocyanine and a second phthalocyanine of tetrafluoro hydroxygallium phthalocyanine.
The disclosures of all of the aforementioned publications, laid open applications, copending applications and patents are totally incorporated herein by reference.